DEV Community

Fathin Dosunmu
Fathin Dosunmu

Posted on • Originally published at agentsim.dev

Fix: Stripe 'This phone number cannot be used for verification' with AI Agents

#ai #python #stripe #automation

If you're building AI agents that need to create Stripe accounts, you've hit this wall:

This phone number cannot be used for verification.
Enter fullscreen mode Exit fullscreen mode

Your agent fills out the form perfectly, reaches phone verification, and — rejected. This guide explains exactly what's happening and how to solve it with real SIM-backed numbers.

Why Stripe Blocks Your Number

Stripe performs carrier lookups against multiple databases before sending any verification SMS:

  1. LERG (Local Exchange Routing Guide) — The authoritative database of North American phone numbers
  2. NPAC (Number Portability Administration Center) — Tracks number porting between carriers
  3. Real-time HLR queries — Verify active network registration on the carrier side

If your number comes back as voip or nonFixedVoip, it's rejected immediately. The code is never sent.

Provider line_type returned Stripe result
Twilio voip ❌ Blocked
Google Voice voip ❌ Blocked
Vonage voip ❌ Blocked
TextNow voip ❌ Blocked
AgentSIM mobile ✅ Passes

Why Twilio/VoIP Numbers Fail

Every VoIP provider's number ranges are catalogued in LERG. When Stripe queries:

{
  "number": "+19875551234",
  "carrier": "Twilio Inc",
  "line_type": "voip"
}
Enter fullscreen mode Exit fullscreen mode

Instant rejection. This isn't a bug — it's by design. Financial services block VoIP to prevent synthetic identity fraud.

The Fix: Real SIM Numbers via AgentSIM

AgentSIM provisions actual SIM-backed phone numbers from carriers like T-Mobile. These return mobile in carrier lookups because they ARE mobile numbers.

Install 

pip install agentsim-sdk
Enter fullscreen mode Exit fullscreen mode

Basic Usage 

import agentsim

agentsim.configure(api_key="asm_live_xxx")

async with agentsim.provision(agent_id="stripe-setup", country="US") as num:
    # num.number is a real mobile number (E.164 format)
    print(f"Using: {num.number}")  # +14155552671

    # Enter the number in Stripe verification form
    await enter_phone_on_stripe(num.number)

    # Wait for the OTP to arrive via real SMS
    otp = await num.wait_for_otp(timeout=60)
    print(f"Code: {otp.otp_code}")  # 391847

    # Enter the code — verification passes
    await enter_code_on_stripe(otp.otp_code)
# Number auto-released when context exits
Enter fullscreen mode Exit fullscreen mode

With Playwright (Full Automation) 

import agentsim
from playwright.async_api import async_playwright

agentsim.configure(api_key="asm_live_xxx")

async def verify_stripe_account():
    async with async_playwright() as p:
        browser = await p.chromium.launch()
        page = await browser.new_page()
        await page.goto("https://dashboard.stripe.com/register")

        await page.fill("[name=email]", "agent@company.com")

        async with agentsim.provision(
            agent_id="stripe-setup",
            country="US"
        ) as num:
            await page.fill("[name=phone]", num.number)
            await page.click("button:has-text(\"Send code\")")

            otp = await num.wait_for_otp(timeout=60)

            await page.fill("[name=code]", otp.otp_code)
            await page.click("button:has-text(\"Verify\")")

        await browser.close()
Enter fullscreen mode Exit fullscreen mode

With MCP (Claude Code / Cursor / Windsurf)

If you're using an AI coding agent, AgentSIM has a native MCP server:

{
  "mcpServers": {
    "agentsim": {
      "url": "https://mcp.agentsim.dev/mcp",
      "headers": {
        "Authorization": "Bearer asm_live_xxx"
      }
    }
  }
}
Enter fullscreen mode Exit fullscreen mode

Then your agent can call provision_number and wait_for_otp as MCP tools directly.

Why AgentSIM Numbers Pass

Check VoIP Number AgentSIM Number
LERG lookup voip mobile
Carrier name Twilio Inc T-Mobile USA
HLR query No network reg Active on tower
Fraud score High (70-90) Clean (0-10)

AgentSIM uses real SIM cards on real carrier networks. The numbers aren't spoofed or masked — they're genuine mobile numbers that pass every verification check.

Cost Comparison

Approach Monthly cost Stripe success rate
Twilio $1-15/number 0%
Google Voice Free (ToS risk) 0%
AgentSIM $0.99/session 100%

10 free sessions per month. No subscription required.

Get Started

Stop fighting VoIP detection. Use real mobile numbers that work.

Top comments (0)